Add Linux support

.github/workflows/ci.yml

@@ -3,7 +3,7 @@
 # Category A (tools-version 6.2 + macOS 26 min): macos-26 + Swift 6.2
 # Category B (tools-version 6.2 + older macOS):  macos-15 + 6.2, macos-26 + 6.2
 # Category C (tools-version 6.0):                macos-15 + 6.0, macos-15 + 6.2, macos-26 + 6.2
-# Linux (if viable):                             ubuntu + Swift 6.0, ubuntu + Swift 6.2
+# Linux:                                          ubuntu + Swift 6.3
 #
 # When Swift 6.3 ships: bump 6.0→6.1 and 6.2→6.3 in Category C
 # When bumping tools-version to 6.2: drop 6.0/6.1, move to Category A or B
@@ -29,6 +29,8 @@ jobs:
         include:
           - os: macos-26
             swift: "6.2"
+          - os: ubuntu-latest
+            swift: "6.3"
     runs-on: ${{ matrix.os }}
     steps:
       - uses: actions/checkout@v6
@@ -39,24 +41,12 @@ jobs:
         run: swift build -v
       - name: Test
         run: swift test -v
-  test-linux:
-    name: Test on Linux
-    runs-on: ubuntu-latest
-    container:
-      image: swift:6.2
-    steps:
-      - uses: actions/checkout@v6
-      - name: Build
-        run: swift build -v
-      - name: Test
-        run: swift test -v
   lint:
     name: Run SwiftLint
-    runs-on: macos-latest
+    runs-on: ubuntu-latest
+    container: ghcr.io/realm/swiftlint:latest
     steps:
       - uses: actions/checkout@v6
-      - name: Install SwiftLint
-        run: brew install swiftlint
       - name: Run SwiftLint
         run: swiftlint --strict
   swift-format:

.github/workflows/doc.yml

@@ -17,7 +17,7 @@ concurrency:
 jobs:
   build:
     name: Build Documentation
-    runs-on: macos-26
+    runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v6
       - uses: SwiftyLab/setup-swift@latest

Package.swift

@@ -39,17 +39,15 @@ let package = Package(
   swiftLanguageModes: [.v5, .v6]
 )
 
-#if os(macOS)
-  package.targets.append(
-    .executableTarget(
-      name: "SwiftCIFP_E2E",
-      dependencies: [
-        "SwiftCIFP",
-        .product(name: "ArgumentParser", package: "swift-argument-parser"),
-        .product(name: "ZIPFoundation", package: "ZIPFoundation"),
-        .product(name: "Progress", package: "Progress.swift")
-      ],
-      swiftSettings: approachableConcurrency
-    )
+package.targets.append(
+  .executableTarget(
+    name: "SwiftCIFP_E2E",
+    dependencies: [
+      "SwiftCIFP",
+      .product(name: "ArgumentParser", package: "swift-argument-parser"),
+      .product(name: "ZIPFoundation", package: "ZIPFoundation"),
+      .product(name: "Progress", package: "Progress.swift")
+    ],
+    swiftSettings: approachableConcurrency
   )
-#endif
+)

Sources/SwiftCIFP/LinuxLocalization.swift

@@ -0,0 +1,20 @@
+//  `String(localized:)` comes from FoundationInternationalization on Apple platforms but
+//  is unavailable on Linux. This package uses its default ("en") localization text as the
+//  lookup key, so on Linux we resolve each key to itself. Excluded on Apple, where the
+//  real Foundation API is used.
+
+#if !canImport(Darwin)
+  import Foundation
+
+  extension String {
+    init(
+      localized key: String,
+      table _: String? = nil,
+      bundle _: Bundle? = nil,
+      locale _: Locale? = nil,
+      comment _: StaticString? = nil
+    ) {
+      self = key
+    }
+  }
+#endif